Showing papers by "Government of Canada published in 1992"

Freshwater biomonitoring and Chironomidae

Abstract: The use of Chironomidae in the biomonitoring of fresh waters is reviewed. Examples are given for levels of organization from organism to ecosystem, and a separate consideration is devoted to toxicity studies. Morphological deformities and life-history responses of Chironomidae to contaminants are common organism-level indicators. At the species-assemblage level, the classic lake trophic classification scheme, its contemporary derivatives, and paleolimnological approaches have been used extensively. Chironomidae also are essential components of quantitative and qualitative (rapid assessment) community approaches to biomonitoring. Examples of chironomids as components of ecosystem-level studies are rare, but even the few studies done show their value for this purpose. In toxicity testing, Chironomidae frequently are used in single species acute, single species chronic, and multispecies tests for a variety of stressors; Chironomidae could be used profitably in any expansion of toxicity testing involving macroinvertebrates. The review indicated that more emphasis on Chironomidae is required in studies of biochemical and physiological indicators of contaminants (organism level), and on Chironomidae as sentinel organisms (population level). Extensive use of Chironomidae in biomonitoring of fresh waters is consistent with the abundance and taxa richness of this group in natural habitats.

A Hierarchical Model of Participatory Decision-Making, Job Autonomy, and Perceived Control

Abstract: Participative decision-making and job autonomy have been linked to perceived control, however, there has been some ambiguity in how this relationship has been approached in the literature. Researchers have generally sought to maintain the conceptual distinction among the constructs but have treated measures of the constructs as if they were indicators of a single underlying control dimension or disposition. The present study tests the plausibility that a hypothetical general control factor influences responding on several measures of perceived job autonomy and participative decision-making at work. Hierarchical confirmatory factor analysis in samples of teachers and computer company employees supported a model in which measures of separate job autonomy dimensions, general job autonomy, perceptions of participative climate at work, and perceptions of control at work all were related to a second order control factor. The second order control factor was shown to be distinct from perceptions of one's supervis...

Effects of forest fire and drought on acidity of a base-poor boreal forest stream: similarities between climatic warming and acidic precipitation

Abstract: In a boreal forest catchment in the Experimental Lakes Area in northwestern Ontario, wildfire caused an increase in the concentrations of strong acid anions and base cations of the stream. In the naturally base-poor Northwest (NW) Subbasin, a 1980 wildfire caused exports of strong acid anions to increase more than export of base cations, causing a 2.5 fold increase in the acidity of the stream. Mean annual stream pH declined from 5.15 prior to fire to 4.76 two years after fire. Acid-neutralizing capacity (ANC), calculated as the difference between total base cations and strong acid anions, decreased to 20% of pre-fire values. Sulfate and chloride were the strong acid anions responsible for the decline in ANC, increasing four-fold. While nitrate increased eleven-fold, concentrations were too low to significantly affect ANC. There was a significant correlation between weekly sulfate concentration and base cation concentration (r 2 = 0.83) in the two years after fire. Recovery of ANC was caused by the more rapid decline in concentration of sulfate than by changes in base cations. Drought produced a similar but weaker response than fire, with increased sulfate concentrations and decreased stream pH. Climatic warming that increases drought and fire frequency would have effects that mimic the impacts of acidic precipitation (i.e. higher sulfate concentrations and acidic stream waters). Areas which have higher concentrations of stored S from past acid precipitation or have large areas of peatlands in the watershed may have aggravated losses of S and H+ after drought and fire.

Effect of deoxynivalenol on neurotransmitters in discrete regions of swine brain.

Abstract: The effect of deoxynivalenol (DON, vomitoxin) on brain amine levels was investigated in swine. DON, a trichothecene mycotoxin, causes suppression of feed intake (anorexia) in susceptible species. Following acute administration of DON to pigs (0.25 mg/kg, IV), concentrations of endogenous catecholamines norepinephrine (NE), dopamine (DA), 3,4-dihydroxyphenyl-acetic acid (DOPAC), and homovanillic acid (HVA), and the indoleamines, 5-hydroxytryptamine (5HT, serotonin) and 5-hydroxyindoleacetic acid (5HIAA) were determined in five brain regions, periodically during the 24 h post-dosing. Analysis was carried out by high performance liquid chromatography, using electrochemical detection.

TTCN: the international notation for specifying tests of communications systems

Abstract: Over a period of about eight years the International Organization for Standardization (ISO) developed and standardized a testing methodology and framework for testing protocol implementations for conformance to OSI standards. As part of that work, a standardized test notation, the Tree and Tabular Combined Notation (TTCN), was developed and used for precise specification of abstract test suites. This paper explains and illustrates, using X.25 examples, the basic concepts of TTCN in the context of the standardized OSI conformance testing methodology and framework (ISO IS 9646). A brief description of the most recent work on enhancements to TTCN and examples of widely available TTCN tools are also presented.

A welfare evaluation of technology transfer to joint ventures in the developing countries

Abstract: It is observed that foreign firms do not transfer state-of-the-art technologies to the developing countries. It is also observed that many developing countries are not reducing the restrictions on foreign ownership. This article analyses the effect of restricting foreign ownership of joint ventures in the developing countries. It demonstrates that restrictions on the foreign share of ownership may result in joint ventures that produce outdated low-tech products. Therefore, allowing a higher share of foreign ownership raises the quality of the technology transferred by the foreign film, but this is shown to have an ambiguous effect on the developing country's welfare.

Influence of surface films on the fate of deltamethrin following aerial application to prairie ponds

Abstract: The dissipation of the insecticide deltamethrin was studied in natural prairie ponds (0 3–1 3 ha, 1–1 5 m depth) following aerial application Four ponds were treated at normal field rates (7 5 g/ha) with deltamethrin, two in June 1986 and two others in June 198− Parts per billion concentrations of deltamethrin were observed in the surface microlaver (0 12 mm, sampled with a glass plate) in all treatments during the first 8 to 12 h after application Levels of deltamethrin were about 1000-fold lower in subsurface water (10–20 cm depth) Pseudo first order half-lives of deltamethrin in the surface film varied from 0 6 to 5 h and were influenced by macrophvte density and amount of sprav deposit Half-lives of deltamethrin in subsurface waters were less variable, averaging 14 h Deltamethrin was not detected in sediments (0–2 5 cm depth containers, detection limit 10 ng/g dry weight) following sprav application in either year The stereoisomer (α R, 1R/α S 1S-cis-) was detected in subsurface water along with a cyclopropvl acid derivative (DBCA) and phenoxybenzoic acid (PBA) Concentrations of DBCA and PBA 10 to 100 fold higher than that of the parent compound persisted in subsurface water for 18 to 25 d after spray deposition The surface film influenced the overall fate of deltamethrin by reducing diffusive transport to subsurface waters and increasing the amount of the insecticide available for volatilization and degradation

Empirical Tests for Allocative Efficiency in the Local Public Sector

Abstract: This article reports evidence from two tests for allocative efficiency in the local public sector using micro-based data. The first test is based on Brueckner's (1979, 1982) theoretical result that a nonpositive relationship between public services and residential property values is a definite indicator of over provision of local public goods beyond optimal levels in the case of typical mixed communities, that is, communities having substantial business property. This article points out the limitations of Brueckner's empirical analysis and provides a stronger empirical test of allocative efficiency in the local public sector using micro-based data. An alternative test that uses the criterion that, when the level of local spending is optimal, a balanced budget change in local spending and residential property taxation should leave residential property values unaltered, is also presented. Both the tests suggest overprovision of local public goods in metropolitan Edmonton, Canada.